Valve train devices are known having a mechanism for switching over the stroke of gas exchange valves. The invention is based on a valve train, in which the gas exchange valves, in particular inlet valves and outlet valves of an internal combustion engine, are directly or indirectly actuated by means of a camshaft. To switch over the valve stroke, adjacent cams with different cam shapes, which are combined to form a cam unit, are provided on the camshaft. By means of an axial displacement of the cam units on the camshaft, the stroke of the gas exchange valves is varied in accordance with the contour of the cams. For the displacement of the cam units, an adjusting shaft running parallel to the camshaft with corresponding elements for engagement on the axially displaceable components, for example cam units, is provided. The adjusting shaft is rotatably mounted in a housing parallel to the camshaft in a plurality of shaft bearings. A housing can be taken to mean a cylinder head, a ladder-type frame, modules or other mechanisms for receiving an adjusting shaft. At least one adjusting mechanism, which is associated with a cam unit for the direct or indirect actuation of gas exchange valves, is mounted on the adjusting shaft.
A rotatable adjusting shaft, which is arranged parallel to a camshaft, on which adjusting shaft two adjusting mechanisms are non-rotatably arranged and two drivers that can be axially displaced on the adjusting shaft for switching over the valve between two different cam profiles of a cam assembly, which is axially displaceable on the camshaft, are arranged between the adjusting mechanisms, is described in the patent DE 10 2008 061 440 B3. By rotating the adjusting shaft, the drivers are axially displaced on the adjusting shaft, the rotation taking place by means of the camshaft. For this purpose, a toothed wheel, which is non-rotatable but axially displaceable and which, to rotate the adjusting shaft, is brought into engagement with a tooth segment arranged on the camshaft by means of a drive arranged on the adjusting shaft, is arranged on the adjusting shaft.
An adjusting shaft arranged parallel to a camshaft, which can be connected by means of a control gear to the camshaft, so the adjusting shaft, when an operative connection is produced to the camshaft, can be rotated thereby, so a cam assembly provided with different cam profiles is axially displaced on the camshaft by means of drivers and a switching gate, is known from patent application DE 10 2009 057 691 A1. The control gear according to the invention to connect and separate the camshaft with respect to the adjusting shaft consists of a one-armed or multi-armed lever system and a profiled gate part. The lever system is rigidly arranged on the adjusting shaft. The gate part is non-rotatably and axially displaceably arranged on the camshaft, it being possible to bring it into engagement by means of an actuator with the lever system in a switchable manner and to separate it.
The drawback of the technical solutions known from the prior art is the high installation space requirement necessary to rotate the adjusting shaft. These solutions can therefore only be used with correspondingly configured cylinder head hoods or adequately large rotation installation space in the region of the adjusting shaft to be able to accommodate the corresponding components.